WO2018195089A1 - Procédés de stabilité de tension de sortie précise et de compensation de température de générateurs de rayons x à haute tension dans les environnements à haute température d'un trou de forage - Google Patents

Procédés de stabilité de tension de sortie précise et de compensation de température de générateurs de rayons x à haute tension dans les environnements à haute température d'un trou de forage Download PDF

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WO2018195089A1
WO2018195089A1 PCT/US2018/027986 US2018027986W WO2018195089A1 WO 2018195089 A1 WO2018195089 A1 WO 2018195089A1 US 2018027986 W US2018027986 W US 2018027986W WO 2018195089 A1 WO2018195089 A1 WO 2018195089A1
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Prior art keywords
control mechanism
generator
voltage generator
voltage
temperature
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PCT/US2018/027986
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English (en)
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Philip Teague
Long Yu
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Philip Teague
Long Yu
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Application filed by Philip Teague, Long Yu filed Critical Philip Teague
Priority to EP18722353.2A priority Critical patent/EP3613262A1/fr
Priority to CA3060534A priority patent/CA3060534C/fr
Priority to AU2018255281A priority patent/AU2018255281B2/en
Publication of WO2018195089A1 publication Critical patent/WO2018195089A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
    • G01V5/04—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging
    • G01V5/08—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays
    • G01V5/10—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using neutron sources
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
    • G01V5/04—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging
    • G01V5/08—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays
    • G01V5/12—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using gamma or X-ray sources
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/10—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode arranged for operation in series, e.g. for multiplication of voltage
    • H02M7/103—Containing passive elements (capacitively coupled) which are ordered in cascade on one source
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/10—Power supply arrangements for feeding the X-ray tube
    • H05G1/12—Power supply arrangements for feeding the X-ray tube with dc or rectified single-phase ac or double-phase
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/10—Power supply arrangements for feeding the X-ray tube
    • H05G1/20—Power supply arrangements for feeding the X-ray tube with high-frequency ac; with pulse trains
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/265—Measurements of current, voltage or power
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/32—Supply voltage of the X-ray apparatus or tube
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/54—Protecting or lifetime prediction
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
    • G21G4/00—Radioactive sources
    • G21G4/02—Neutron sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration

Definitions

  • the present invention relates generally to methods and means for accurately controlling the output stability of a generator that controls an electronic radiation source when used in a high temperature environment, such as within the domain of oil and gas well logging.
  • Well or borehole logging is the practice of making an accurate record, known as a well log, of the geologic formations through which a borehole creates a path or conduit.
  • Well logging activities are performed during all phases of an oil and gas well's development; drilling and evaluation, completion, production and abandonment.
  • the oil and gas industry logs rock and fluid properties to find hydrocarbon-bearing strata in the formations intersected by the borehole.
  • the logging procedure consists of lowering a tool on the end of a wireline into the well to measure the properties of the formation. An interpretation of these measurements is then made to locate and quantify potential zones containing hydrocarbons and at which depths these zones exist.
  • Logging is usually performed as the logging tools are pulled out of the hole. This data is recorded in real-time via a data connection to the surface logging unit or using a memory unit aboard the tool to create either a printed record or electronic presentation called a well log which is then provided to the client. Well logging is performed at various intervals during the drilling of the well and when the total depth is drilled.
  • Density logging is the practice of using a specific well logging tool to determine the bulk density of the formation along the length of a wellbore. The bulk density is the overall density of a rock including the density of the minerals forming the rock and the fluid enclosed in the pores within the rock.
  • a radioactive isotope-based source usually Cesium 137 ( 137 Cs)
  • Cesium 137 137 Cs
  • a radioactive isotope-based source usually Cesium 137 ( 137 Cs)
  • Cesium 137 137 Cs
  • a radioactive isotope-based source usually Cesium 137 ( 137 Cs)
  • Cesium 137 137 Cs
  • a radioactive isotope-based source usually Cesium 137 ( 137 Cs)
  • Cesium 137 ( 137 Cs) applied to the wall of the borehole emits gamma rays into the formation so these gamma rays may be thought of as high velocity particles which collide- with the electrons of the atoms that compose the formation.
  • the gamma rays lose some of their energy to the electrons, and then continues with diminished energy.
  • This type of interaction is known as Compton scattering.
  • a proportion of the scattered gamma rays reach detectors located at fixed distances from the source,
  • the typical regulatory limit for the amount of 137 Cs which may be used during a logging operation is a maximum of 1.3 Curie.
  • density logging operations a certain number of photons per second are required to enter into the detectors to ensure a high enough statistic for the purposes of data quality consistency and interpretation.
  • density logging operations are normally performed such that the tool is moved at a rate of 1,800 feet per hour to ensure sufficient photons enter the detectors at any particular depth to offer a data resolution acceptable to the client (typically a repeatability to O.Olg/cc density). In a 15,000ft long well, this can translate to just over 8 hours of logging time, bottom to surface (or at least 2 hours in the zone of the reservoir).
  • prior art discloses methods to monitor the output radiation of x-ray tubes, and to use the changes in resultant radiation output levels as input modify the input voltage of the generator.
  • modification of x-ray output after it has already been produced would not help correct the log data that would already have been detrimentally affected by the changes in x-ray energy/output.
  • a resistor-based feedback loop may be implemented such that the output potential of the multiplier can be monitored.
  • the capacitance of the capacitors in the multiplier reduces with ambient temperature, the natural harmonic frequency of the multiplier will increase as a function of temperature. If the input frequency of the ladder is fixed (which is typical), then the result will be a reduction in the efficiency of the multiplier with increase in ambient temperature, and the output voltage of the generator will reduce.
  • NPO which exhibits a low capacitance per unit volume (and therefore very large in comparison to equivalent value capacitor materials), the majority of capacitor materials that are useful within a downhole tool tend to exhibit a variable capacitance with respect to environmental temperature. Within high- temperature environments the capacitance can degrade to such an extent that efficiency of the high- voltage ladder will degrade such that thermal-run-away and failure can be expected.
  • a DC to DC high voltage power supply system including a transistor chopper DC to AC inverter type circuit and a high voltage output transformer that includes an extra secondary winding, hereinafter referred to as a tertiary winding, which- generates a feedback voltage which is proportional to the high voltage output.
  • a passing element for example, a transistor, is located between the DC input voltage and the DC to AC inverter circuit and is controlled by the voltage generated by the tertiary winding to provide a highly regulated DC input voltage to said inverter circuit.
  • the DC voltage appearing across a tertiary winding rectifier circuit is coupled to a filter circuit comprising capacitors in combination with a temperature compensating resistance ⁇
  • US 5,023,768 to Collier discloses a high voltage, high power DC power supply that includes a single turn primary winding driven through a resonating capacitor by an AC source having s a frequency in excess of about 100 kHz.
  • the primary winding includes a pair of concentric cylindrical metal walls having opposite ends electrically connected to each other.
  • a volume between the walls includes plural secondary winding assemblies, having different axial positions along the walls.
  • Each of the assemblies includes an annular magnetic core surrounding the interior wall, a winding on the core and a voltage-doubling rectifier. DC voltages developed across each secondary winding assembly by the rectifier are added together to provide the high voltage, high power output.
  • US 5,400,385 to Blake et al. discloses a supply for a high bias voltage in an X-ray imaging system has an inverter and a voltage multiplier that produce an alternating output voltage in response to control signals.
  • a voltage sensor produces a signal indicating a magnitude of the output voltage.
  • a circuit determines a difference between the sensor signal and a reference signal that specifies a desired magnitude for the output voltage and that difference is integrated to produce an error signal.
  • the error signal preferably is summed with a precondition signal that is an approximation of a nominal value for the signal sum and the summation producing a resultant signal.
  • Another summation device arithmetically combines the resultant signal and the sensor signal with a signal corresponding to a one-hundred percent duty cycle of the inverter operation in order to produce a duty cycle command:
  • An inverter driver generates the inverter control signals that have frequencies defined by the resultant signal and have duty cycles defined by the duty cycle command.
  • a unique state machine is described which generates those control signals.
  • US 4,641,330 to Herwig et al. discloses of a high voltage supply circuit for an x-ray tube includes a high voltage transformer having a primary side driven by voltage pulses generated by a drive circuit.
  • the drive circuit includes sub-circuits for controlling the pulse repetition frequency, which is selected as equal to a parallel resonant frequency of a high voltage generator connected to the secondary side of the transformer, for the purpose of saving energy.
  • the drive circuit also includes a sub-circuit for controlling the pulse duration, with the filament voltage in the x-ray tube being regulated by this pulse duration.
  • US 7,564,948 to Wraight et al. discloses of an x-ray source being used as a replacement for a chemical source during density logging along with various means of arranging the apparatus and associated power-supply, also teaches of the means of filtering the primary beam from the x-ray source such that a filtered dual-peak spectrum can be detected by a reference detector which is then used to directly control (feedback) the x-ray tube voltage and current for stability purposes.
  • the patent discloses only a compact x-ray device (bipolar) with a grid, a power supply in the form of a Cockcroft- Walton rolled up into a cylinder between two Teflon cylinders in order to save space, and the aforementioned filtered reference detector method.
  • US 8,481,919 to Teague teaches a means of creating and controlling the electrical power necessary, by serially stepping up the DC reference and creating high potential field control surfaces, to control either a bipolar or unipolar x-ray tube for the purposes of replacing chemical sources in reservoir logging.
  • the reference also teaches one or more moveable/manipulatable beam hardening filters and rotating light-house collimation on the source, the use of gaseous insulators including SF6 as an electrical insulator in a downhole x-ray generator.
  • the reference does not disclose a method of using the increased output of the x-ray device to enable longer offset detectors to enable analysis of the non-invaded zone of the formation. It also fails to teach of a method to increase the permissible count rate within a detector volume by doubling the number of PMTs for a given detector volume.
  • a control mechanism for a high-voltage generator for supplying voltage and current to an electronic radiation source in high-temperature environments including at least one voltage feedback loop for monitoring the output of the generator; at least one environmental temperature monitor; a control bus; and at least one control processor.
  • a method of controlling a high-voltage generator that powers an electronic radiation source in high-temperature environments including at least: measuring the output voltage of the generator; measuring the temperature within the generator's environment, using a control mechanism to modify an associated driving frequency, and using a control mechanism to modify an associated driving pulse-train, such that the change in properties of the electronic components of the generator as a result of changes in environmental temperature are characterized and the generator's driving signals modified to maintain optimally efficient input parameters for a specific environmental temperature.
  • Figure 1 illustrates the relationship between the capacitance of four different types of capacitor materials and environmental temperature.
  • Figure 2 illustrates a high-voltage generator connected to an electronic radiation source, a resistor-based voltage feedback loop, a temperature sensor, and a control input processor.
  • Figure 3 illustrates a H-bridge configured driving circuit, pulse-width modulated inputs, voltage inputs, ground potential, and an output transformer.
  • Figure 4 illustrates two high-voltage generators connected to an electronic radiation source in bi-polar configuration, resistor-based voltage feedback loops, temperature sensors, control input processors, and a communications bus all employed to maintain a consistent potential across the electronic radiation source.
  • Figure 5 illustrates two high-voltage generators connected to an electronic radiation source in bi-polar configuration, resistor-based voltage feedback loops,_ temperature sensors, control input processors, and a communications bus all employed to maintain a consistent potential across the electronic radiation source.
  • Figure 6 illustrates three different control-train input profiles examples for pulsed-input modulation of high- voltage generator.
  • a control mechanism for a high-voltage generator that powers an electronic radiation source in high-temperature environments is provided, the tool including at least a voltage feedback loop for monitoring the output of the generator, a temperature monitor, a control bus and a control processor.
  • Figure 1 illustrates the relationship between the percentage change in capacitance [101] of four different types of capacitor materials and environmental temperature in degrees Celsius [102].
  • NP0 [103] which exhibits a low capacitance per unit ' volume
  • the majority of capacitor materials that are useful within a downhole tool tend to exhibit a variable capacitance with respect to environmental temperature [102].
  • the capacitance [101] can degrade to such an extent that efficiency of the high- voltage ladder will degrade such that thermal-run-away and failure can be expected.
  • Figure 2 illustrates a high- voltage ladder [201], driving a unipolar electronic radiation source [202] based upon a multistage Greinacher multiplier (Cockcroft- Walton), may be driven by an alternative current waveform [204] that has been generated by a H-bridge circuit [203].
  • a resistor-based feedback loop [205] may be implemented such that the output potential of the multiplier can be monitored.
  • the capacitance of the capacitors [206] in the multiplier reduces with ambient temperature, the natural harmonic frequency of the multiplier will generally increase as a function of temperature. If the input frequency of the ladder is fixed (which is typical), then the result will be a reduction in the efficiency of the multiplier with increase in ambient temperature, and the output voltage of the generator will reduce.
  • the ambient temperature can be monitored [208] and used as an input into the control algorithm.
  • the drive frequency of the multiplier can be made to increase to match the increasing natural frequency of the multiplier as a function of ambient temperature.
  • the whole generator can be characterized to ascertain the most optimum (efficient) frequency of the ladder as a function of temperature, and that data used to shape the control algorithm, the result being that multiplier efficiency and output voltage remain constant even into high ambient temperature regimes.
  • FIG. 3 illustrates a typical H-bridge configured driver using Field Effect Transistors (FETs).
  • the HV in direct-current potential [303] will define the output Peak-peak voltage of the H-bridge into the transformer [306] and consequently, determine the output voltage of multiplier [304] compared to a reference potential [305], such as ground.
  • a processor [207] can be configured such to produce Pulse Width Modulation (PMW) signals to inputs [301, 302] on either side of the H-bridge to control the frequency and duty cycle of the output waveform.
  • the frequency of the output waveform can be the result of an algorithm that uses temperature gauges [208] as an input to determine the optimum resonant frequency for multiplier as a function of ambient temperature.
  • FIG. 4 illustrates a bipolar x-ray source tube [401].
  • a bi-polar configured electronic source tube does not possess a grounded anode or cathode.
  • the negative [402] and positive [403] generators work together to determine the overall tube potential [411], which is a combination of the output of each multiplier [409, 410].
  • the effective load on each multiplier changes as a function of the operating point of the other pole's operating set-point, the potential for chaotic behavior to arise is possible, unless the setpoint for the output of each generator is monitored accurately.
  • One of the two generators' controllers [406, 407] can act as the overall system 'master' and the other as the 'slave'.
  • each controller would be responsible of maintaining its own set-point [409, 410] but the control master would ensure that the overall tube potential remains constant by issuing set-point modification instructions over a communications bus [408] between the two generator controllers [406, 407].
  • Figure- 5 illustrates an alternative schematic representation of the bipolar configured drive system.
  • a single pole's generator may contain tens or hundreds of stages, each doubling or tripling the DC potential of the multiplier, it is obvious that controlling the multiplier though modification of the DC input potential to the H-bridge [511, 512] would result in the significant amplification of an variation (or error) in the DC level of the input.
  • input DC level modification isn't an optimum control mechanism if very high output potential accuracy is desired.
  • the responsiveness (or time-base) of the generator is a function of length, capacitance, and operating frequency, it is possible that any output potential feedback or monitoring loop [504, 505] could produce a time-delay into the control system [507, 508]. If correctly filtered, the feedback loop potential can be used for accurate control of the output. As the change in multiplier output as a function of temperature (and therefore, efficiency change) is a separate control dimension to the feedback loop, it would make little sense to attempt to control temperature effects and general output instabilities by real-time control of the DC input level to the multiplier.
  • Figure 6 illustrates three examples of control drive-train inputs shown as high-voltage potential [604] in, referencing ground potential [605], as a function of time [606] in milliseconds.
  • a standard control pulse [601] exhibits a 33% duty cycle; the FET being controlled is outputting 33% of the time in a cyclic function.
  • the second example [602] illustrates the effect of increasing the output frequency of the controlling PWM signal, here the duty cycle remains at 33%, however the frequency has been doubled.
  • the third example [603] illustrates one possible embodiment of a modification (or modulation) of the 'pulse-train'.
  • the duty cycle remains at 33%, but every 3rd pulse is skipped such that, for a short period of time, the amount of pulses (and therefore, energy) being delivered into the multiplier is reduced such that the output of the generator will decrease temporarily as a function of the percentage of skipped pulses in the pulse-train over the time period of the total number of pulses at the set operating frequency.
  • the time taken for this control input to reach the output is dependent upon the number of stages in the multiplier and the operating frequency of the multiplier - typically, the time-based of the generator would be operating frequency divided by the number of discrete multiplier stages.
  • a high- voltage ladder driving a x-ray tube based upon a multistage Greinacher multiplier is driven by an alternative current waveform that has been generated by a H-bridge circuit consisting Field Effect Transistors (FETs).
  • FETs Field Effect Transistors
  • a resistor-based feedback loop is configured such that the output potential of the multiplier can be monitored directly, and the resultant signal fed (comparator) into a microprocessor.
  • the direct-current input potential (for the FETs) will define the output Peak-peak voltage of the H-bridge into the transformer and consequently, determine the output voltage of multiplier.
  • the input potential to the FETs can be controlled by the controller to make large modifications to the output of the generator, such as a 'start-up' where the output of the generator may be required to change from OkV to 300kV, for example.
  • a processor can be configured such to produce Pulse Width Modulation (PMW) signals to either side of the H-bridge to control the frequency and duty cycle of the output waveform.
  • PMW Pulse Width Modulation
  • the frequency of the output waveform is the result of an algorithm that uses temperature gauges as an input to determine the optimum resonant frequency for multiplier as a function of ambient temperature.
  • Said processor is equipped with firmware that controls the input voltage, frequency, duty-cycle and pulse-train configuration of the FET-based H- bridge.
  • the natural harmonic frequency of the multiplier will increase as a function of ambient temperature.
  • the processor is configured such to control the operating frequency of the H-bridge, the ambient temperature can be monitored and used as an input into a control algorithm.
  • the drive frequency of the multiplier can be made to increase to match the increasing natural frequency of the multiplier as a function of ambient temperature.
  • the whole generator can be characterized to ascertain the most optimum (efficient) frequency of the ladder as a function of temperature, and that data used to shape the control algorithm. The result being that multiplier efficiency and output voltage remain constant even into high ambient temperature regimes.
  • a bipolar x-ray tube does not include a grounded anode (as the anode is connected to a second 'positive' generator).
  • the negative and positive generators work together to determine the overall tube potential, which is essentially the combined output of the multipliers. As the effective load on each multiplier changes as a function of the operating point of the other pole's operating set-point, the potentiaL for chaotic behavior is possible, unless the setpoint for the output of each generator is monitored accurately.
  • one of the two generators' controllers acts as the overall system 'master' and the other as the 'slave.' In this manner, each controller is responsible of maintaining its own set-point but the master ensures that the overall tube potential remains constant by issuing set-point modification instructions over a communications bus that links the two controllers.
  • a standard control pulse exhibiting a specific duty cycle i.e., the FET being controlled is outputting a specific percentage of the time in a cyclic function.
  • the output frequency of the PWM signal controlling the ladder may be adjusted by algorithm to compensate for temperature effects in the generator, while the duty cycle remains constant.
  • the firmware in the controller(s) is configured such to affect a modification (or modulation) of the 'pulse-train'.
  • the duty-cycle remains at constant but every 25th pulse is skipped such that, for a short period of time, the amount of pulses (and therefore, energy) being delivered into the multiplier is reduced such that the output of the generator decreases temporarily as a function of the percentage of skipped pulses in the pulse-train over the time period of the total number of pulses at the set operating frequency.
  • the time taken for this control input to reach the output is dependent upon the number of stages in the multiplier and the operating frequency of the multiplier - typically, the time-base of the generator is the operating frequency divided by the number of discrete multiplier stages.
  • control algorithm of the processor would determine what short-term changes would need to be made to the output of the multiplier, and effect real-time changes to the pulse train, such as changing from 100/100 equal pulses to 98/100 (where in 1 in 50 are skipped), or where 96/100 equal pulses (1 in 25 skipped) and then reverting to the original set-point as necessary to ensure a highly accurate output stability - changes of a few volts.
  • such stability in operation permits an electronic radiation source to exhibit statistical output stability similar to a chemical source, thereby enabling their use within downhole logging tools where the statistical repeatability of the measurement is paramount.
  • high logging speeds are achieved without forsaking statisticaf repeatability/accuracy over the mission time (or log time) of the logging tool as a function of temperature, which typically varies with depth and mission time.
  • the output of the generator feeding the electronic radiation source remains constant as a function of ambient temperature, regardless of the choice of capacitance substrate in the generator.
  • discrete modification of the pulse-train permits very precise control of the generator output.
  • very accurate digital control by direct quantization of the energy entering the multiplier permits a high-speed control mechanism that is characterizable, such that control of two inter-linked generators (in the case of a bipolar tube) is achievable with a high degree of output stability.
  • the electronic radiation source controlled by the method is an electronic x-ray source.
  • the electronic radiation source controlled by the method is an electronic pulsed-neutron generator source.

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  • General Engineering & Computer Science (AREA)

Abstract

La présente invention concerne un mécanisme de commande pour un générateur à haute tension pour fournir une tension et un courant à une source de rayonnement électronique dans des environnements à haute température, le mécanisme de commande comprenant au moins une boucle de rétroaction de tension pour surveiller la sortie du générateur ; au moins un dispositif de surveillance de température environnementale ; un bus de commande ; et au moins un processeur de commande. L'invention concerne en outre un procédé de commande d'un générateur à haute tension qui alimente une source de rayonnement électronique dans des environnements à haute température, le procédé comprenant au moins: la mesure de la tension de sortie du générateur ; la mesure de la température dans l'environnement du générateur, l'utilisation d'un mécanisme de commande pour modifier une fréquence d'entraînement, et l'utilisation d'un mécanisme de commande pour modifier un train d'impulsions d'entraînement, de sorte que des changements de propriétés des composants électroniques du générateur en conséquence de changements de température ambiante soient caractérisés et les signaux d'entraînement du générateur modifiés pour maintenir des paramètres d'entrée ayant une efficacité optimale pour une température ambiante spécifique.
PCT/US2018/027986 2017-04-17 2018-04-17 Procédés de stabilité de tension de sortie précise et de compensation de température de générateurs de rayons x à haute tension dans les environnements à haute température d'un trou de forage WO2018195089A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP18722353.2A EP3613262A1 (fr) 2017-04-17 2018-04-17 Procédés de stabilité de tension de sortie précise et de compensation de température de générateurs de rayons x à haute tension dans les environnements à haute température d'un trou de forage
CA3060534A CA3060534C (fr) 2017-04-17 2018-04-17 Procedes de stabilite de tension de sortie precise et de compensation de temperature de generateurs de rayons x a haute tension dans les environnements a haute temperature d'un tr ou de forage
AU2018255281A AU2018255281B2 (en) 2017-04-17 2018-04-17 Methods for precise output voltage stability and temperature compensation of high voltage x-ray generators within the high-temperature environments of a borehole

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US201762486250P 2017-04-17 2017-04-17
US62/486,250 2017-04-17
US15/955,263 2018-04-17
US15/955,263 US10571599B2 (en) 2017-04-17 2018-04-17 Methods for precise output voltage stability and temperature compensation of high voltage X-ray generators within the high-temperature environments of a borehole

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WO2018195089A1 true WO2018195089A1 (fr) 2018-10-25

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EP3720254A1 (fr) * 2019-04-04 2020-10-07 Koninklijke Philips N.V. Algorithme actif de compensation de temps de montée et de descente
CN110336473B (zh) * 2019-07-11 2021-05-18 珠海万力达电气自动化有限公司 一种铁路专用低压电源及半闭环控制方法
US11751316B2 (en) * 2019-11-05 2023-09-05 Gulmay Limited Power transfer and monitoring devices for X-ray tubes
US11683879B2 (en) * 2020-06-09 2023-06-20 Moxtek, Inc. Scanning x-ray system
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Also Published As

Publication number Publication date
AU2018255281A1 (en) 2019-12-05
CA3060534A1 (fr) 2018-10-25
CA3060534C (fr) 2022-03-15
US10571599B2 (en) 2020-02-25
AU2018255281B2 (en) 2020-10-08
EP3613262A1 (fr) 2020-02-26
US20180239052A1 (en) 2018-08-23

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